The recent success with the Stargardt disease gene shows how a rare macular disease can lead to insight into the common age-related macular degeneration (AMD). This promise that continued progress and success will also lead to a better understanding of macular function and dysfunction as well as AMD. North Carolina macular dystrophy (MCDR1) is a congenital macular dystrophy that was mapped by linkage to chromosome 6 in 1992 by Small et al. The major goals from the original (previous) proposal were directed towards the fine mapping and cloning of the MCDR1 gene. All of these previous goals have been achieved except for the actual identification of the MCDR1 gene and identification of the mutations(s). The current proposal will accomplish this by continuing the ongoing efforts with positional cloning strategies. Specific aim 1 is to continue to ascertain North Carolina macular dystrophy (MCDR1) families in order to try to narrow the genetic interval even further. The current interval has been narrowed to 600 kb by the investigator's laboratory. Specific aim 2 is to continue the identification and characterization of the MCDR1 candidate genes. The group has recently identified 27 new candidate genes from their PACs (P1 artificial chromosomes) within the genomic region. Specific aim 3 is to perform mutations screening of these genes in MCDR1 families. This will be accomplished primarily by protein truncation testing (PTT) if the fragments are 300-1,000 bp in size or by single strand conformation polymorphism (SSCP) if the fragment is less than 300 bp. If no mutations are found in these candidate genes, additional ones will be identified and prioritized. Specific aim 4: Once the MCDR1 gene is identified, AMD patients will be screened for mutations in the MCDR1 gene in order to evaluate its role in AMD and the prevalence of the mutation in the general population. It is expected that the above specific aims will be accomplished within three years. However, because the timing of the identification of the MCDR1 gene is difficult to predict, the future aims of this proposal are discussed in case the gene is found sooner. These future aims and directions are to determine the function of the MCDR1 and to identify other proteins that interact with the MCDR1 gene product since they may also be involved in macular diseases including AMD. Finally, a transgenic, a knockout, and a knock in mouse will be created to better understand MCDR1 function and to create an animal model for future therapeutic attempts.